Currently, mobile communications systems such as mobile phone systems and wireless MANs (Metropolitan Area Networks) have come into common use. In addition, active discussions on next generation mobile communications technology have been continued in order to further increase the transmission speed and capacity of wireless communication. For example, the 3GPP (3rd Generation Partnership Project), which is a standards body, has proposed a communication standard called LTE (Long Term Evolution) which allows communication using a frequency bandwidth up to 20 MHz (see, for example, 3GPP (3rd Generation Partnership Project), “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description”, 3GPP TS 36.300 V9.1.0, 2009-09., and 3GPP (3rd Generation Partnership Project), “Evolved Universal Terrestrial Radio Access (E-UTRA) Radio Resource Control (RRC); Protocol specification”, 3GPP TS 36.331 V9.0.0, 2009-09.). Further, a communication standard called LTE-A (LTE-Advanced) which allows communication using up to five 20-MHz bandwidth carriers (that is, frequency bandwidth up to 100 MHz) has been proposed as a next generation communication standard after the LTE standard (see, for example, 3GPP (3rd Generation Partnership Project), “Feasibility study for Further Advancements for E-UTRA (LTE-Advanced)”, 3GPP TR 36.912 V9.0.0, 2009-09.).
In addition, for some of such communication standards, adoption of a data transmission scheme called MBSFN (Multimedia Broadcast multicast service Single Frequency Network) has been discussed (see, for example, 3GPP (3rd Generation Partnership Project), “Feasibility study for Further Advancements for E-UTRA (LTE-Advanced)”, 3GPP TR 36.912 V9.0.0, 2009-09.). In MBSFN operation, a plurality of base stations transmit same data at the same timing using the same frequency and the same modulation scheme. Data transmitted using MBSFN is sometimes called the “MBMS (Multimedia Broadcast Multicast Service) data”. A mobile station combines signals received from a plurality of base stations, which results in an improvement in reception quality. Note that a method related to MBMS data transmission has been proposed in which user equipment (mobile station) transmits, to a base station apparatus, feedback information reporting that MBMS data fails to meet predetermined quality, and the base station apparatus determines, based on the feedback information, whether to perform adaptive modulation or not (see, for example, Japanese Laid-open Patent Publication No. 2008-278339). In addition, a technique has been proposed in which a base station transmits an MBSFN reference signal related to MBSFN to a mobile station and differentiates subframes used for MBSFN transmission (MBSFN subframes) from non-MBSFN subframes (see, for example, paragraphs [0095] and [0096] of Japanese Laid-open Patent Publication No. 2009-253614).
It is considered to enable, in a mobile communications system capable of using a plurality of frequency bands, like an LTE-A system, a plurality of base stations to transmit same data at the same timing to a mobile station. However, for such a mobile communications system, the problem of how to efficiently use wireless resources of the frequency bands becomes an issue. For example, since having a different structure from a non-MBSFN subframe, an MBSFN subframe may not hold MBMS data together with different types of user data (i.e., non-MBMS data). In addition, MBSFN transmission may be started by a mobile station transmitting a request to a base station. If the mobile station makes a request for MBSFN transmission using an arbitrary frequency band and the base station then starts the MBSFN transmission using the arbitrary frequency bandwidth corresponding to the request from the mobile station, MBSFN subframes incapable of holding other types of user data appear distributedly. This may cause a reduction in the efficiency in wireless resource use.